1. Field of the Invention
The present invention relates to an audio signal/data signal integrated communication system which uses an audio signal channel and a data signal channel, and, more particularly, to an audio signal/data signal integrated communication system which can make effective use of channels.
2. Description of the Related Art
According to a conventional audio signal/data signal integrated communication system, a data terminal can be coupled to a digital telephone which is coupled to a primary transfer line serving to transfer an audio signal and a data signal. An interrupt transfer line separate from the primary transfer line is coupled to the digital telephone to permit a third party to make an interrupt telephone communication over the interrupt transfer line. However, such a digital telephone needs two transfer controllers respectively for the primary transfer line and interrupt transfer line. This inevitably enlarges the telephone and increases the manufacturing cost. For connection of such a telephone, two lines are used on the side of an exchange, thus impairing the system efficiency.
This problem may be solved by preparing a device for exclusive use for the interrupt telephone communication and using the device in parallel with the digital telephone or together with an additional telephone. This, however, requires a large space for device installment and would still have the aforementioned problem of increasing the cost of the total system.